Fall Plant Sale Preview: Woodland Phlox

By Rose James
Duke Class of 2020

Phlox divaricata 'Blue Perfume' is similar
to the 'Blue Moon' variety we'll have at
the Fall Plant sale. Photo by Jason Holmes.

Finding the right color of flowers for your garden can be difficult. I am particular to roses myself, but when it comes to purple and blue blooms, I have to turn to other options. Some of the prettiest shades of lavender I have ever found have come from the Phlox divaricata, commonly called the woodland phlox.

Ranging from lavender to blue, the Phlox divaricata is a small, native wildflower with dainty flowers that bloom in  April and May. It grows to be 8 to 12 inches high and equally as wide. It does well in partial shade to full shade gardens.

As an added bonus to its lush color, the woodland phlox is known to attract hummingbirds and butterflies. If left to grow in your garden, the woodland phlox will form large colonies over time, as wildflowers tend to do.

Woodland phlox in the Terrace Gardens. Photo: J. Holmes.

The Duke Gardens Fall Plant sale will feature the 'Blue Moon' Phlox divaricata, known for its deep violet-blue flowers. Its blooms are not only colorful but very fragrant. The 'Blue Moon' is a good complement for gardens with ferns and hellebores and is certain to please gardeners seeking to bring a variety of color into their gardens.

Fall Plant Sale details:

Date: Saturday, Sept. 30, 2017
Time: 8 a.m.-noon
Membership benefit: Duke Gardens members get 10% off! Join online or on site.
Parking: Free.
Pets not permitted
Wagons + boxes: Our supply is limited; please bring your own if possible, and you'll have more time to spend gathering beautiful plants.
Please see our event page for more information, and we'd love for you to spread the word on Facebook. Thank you!

Plant Sale Preview: Why Plant in Fall?

By Sheon Wilson

Publications coordinator

Fall is the best time to plant a garden, whether you have a vegetable garden, perennial garden, shrubs or trees. It’s prime time to improve your landscape, and Duke Gardens Fall Plant Sale this Saturday will help you meet that goal.

From herbs to shrubs, we'll have a wide variety of plants
that are ideal for this region. Photo by Cecilia Xie

The sale will include plants propagated by Duke Gardens staff and volunteers, along with bulbs, trees, vegetables, shrubs and other delights from local suppliers. Our well-received “Herb Garden in a Box” discount deal is back by popular demand, as well as dorm-friendly succulents and other plants perfect for students. Duke Gardens members will receive 10 percent off every purchase.

Getting your plants into the ground now will give them a strong head start to a healthy spring and summer.

“We are getting into the cooler season, when plants go dormant and put more energy into their root systems,” says Jason Holmes, curator of the Doris Duke Center Gardens. “The root systems are easier to establish during the fall and winter months.”

A complex underground network, roots go into resting mode in the winter, minimizing the basic processes that sustain a plant. The falling temperatures and reduced daylight cause the upper part of a plant to stop growing and enter a state of suspended animation. Without leaves to photosynthesize and make food, the plant’s roots live off of stored sugars.

Plant your tulip bulbs in fall for a spring spectacle.
Photo by Bobby Mottern.

The roots’ ability to sustain life year-round benefits the entire plant. In fall, the soil is warm from summer sun, so the roots can expand with ease until the soil freezes, and thereafter grow more slowly.  In springtime, the plant is prepared to send energy back out to the extremities so blooming can begin. And the roots will have more strength to withstand  often harsh summer soil conditions.

In the Terrace Gardens, horticulturists usually maintain the summer beds through mid-October, and then pull weaker plants and fill the beds with fall color, said Mike Owens, curator of the Historic Gardens.

Use that tip to improve your garden. Remove annuals that have been ravaged by the summer sun and replace them with a splash of color, perhaps some showy and resilient chrysanthemums.

Plant in fall to get a healthy start on a strong
root  system, like that our dawn redwood.

We’ll have gorgeous plants for a variety of garden styles and conditions, and our expert horticulturists and volunteers will be happy to advise you on the best fit for your garden conditions and for the time and energy you have (or don’t have!) to spend caring for your plants. We look forward to seeing you at the sale, and to giving your plants the healthy head start they need. 

Fall Plant Sale details:

Date: Saturday, Sept. 30, 2017
Time: 8 a.m.-noon
Membership benefit: Duke Gardens members get 10% off! Join now or on site.
Parking: Free.
Pets not permitted
Wagons + boxes: Our supply is limited; please bring your own if possible, and you'll have more time to spend gathering beautiful plants.
Please see our event page for more information, and we'd love for you to spread the word on Facebook. Thank you!

Why is fall best for planting?

Jason Holmes, center, 

advises customers about plant selection

at last year's Fall Plant Sale

By Jason Holmes

Ahh, the season of fall is almost upon us, and we gardeners are coming out of summer semi-hibernation, during which we emerged only to water the plants we planted in early spring, hoping they made it through those hot, dry summer months.

Many of us know that fall is the best time to plant shrubs and trees. We hear it all the time. But let’s face it, we see plants we love, with those nice big flowers or that beautiful combination we just have to have, and that sage advice sometimes gets forgotten. For me, buying plants in spring is often an impulse, and I spend much of my time watering those plants on 90- to 100-degree afternoons.

People often ask, “Why is fall the best time to plant?” The answer is simple: As the plants go dormant above ground, roots will continue to grow underground until the ground temperatures fall below 40 degrees Fahrenheit.  So for most of the country, this statement is true from mid-September through mid-December.

Here is an example: if you plant a tree in the spring, it must acclimate to the new site, producing new growth like leaves, flowers and sometimes fruits. It must also produce roots as well! This means you will need to water more often while your tree acclimates to its new situation before the summer heat and often dry weather arrives. Now, plant the same tree during the fall, and soon after the plant will begin to go dormant above ground, but the roots will still have several months to continue growing underground. This is giving the plant a “head start” for the next spring as it produces strong new growth.

Annuals and perennials are great to plant during the spring and fall. As long as they are watered until they are established, they fare very well. I love to plant perennials in the spring, as they are waking up from winter dormancy, because they grow to fill in a space quickly. Perennials are often faster to grow into a space as opposed to trees and shrubs, and this gives us a chance to plant these in both seasons. So it is simple: anyone can plant anytime they want. I just hope I’ve explained well enough why fall is so ideal.

To help prepare you for your fall planting blitz, Sarah P. Duke Gardens will have its Fall Plant Sale on Saturday, Sept. 29, from 9 a.m. to noon. We will have a great variety of bulbs that bloom in late winter to early summer, fantastic perennials, useful herbs for cooking, and many unusual shrubs and trees, too. Many of these plants are propagated from Duke Gardens by dedicated staff and volunteers, who will be there to answer any questions you may have about gardening or plants in general.

If you want first dibs on all the plants, consider joining Friends of Duke Gardens, so you can attend the member pre-sale at 8 a.m. Non-members can join on site. Or call 919-668-1711 to join in advance. We hope to see you there.

Sarah P. Duke Gardens creates and nurtures an environment in the heart of Duke University for learning, inspiration and enjoyment through excellence in horticulture. The Gardens is at 420 Anderson St.

Columnist Jason Holmes is curator of the Doris Duke Center Gardens at Sarah P. Duke Gardens. This column first appeared in the Durham Herald-Sun.

Landscape Plants for N.C. Gardens: Spring

By Kate Blakely

As the last frost date approaches next week, our urge to plant is strong. But some plants fare far better in the Triangle than others, as gardeners often learn by trial and error.

If you’d like some guidance in selecting the best plants for this region and growing them successfully, we’ve got the perfect class for you. “Landscape Plants for North Carolina Gardens: Spring” begins this week and runs for four Thursdays from 10 a.m. to noon.

Robert Mottern, Duke Gardens’ director of horticulture, will teach the class. He shared a few tips to help get you started with soil preparation and plant placement.

The soil in the Triangle area is almost all clay. Clay-based soils can serve as rich ground for gardening, Mottern says, but it has to be loosened to facilitate strong root growth. You must also incorporate organic matter. That means amending the soil with composts, manures and sometimes sand.

Clay does a good job of holding nutrients and water. However, the soil structure of clay can make these nutrients and water unavailable to plants. Adding organic matter and some sand helps break up the clay, releasing vital nutrients and improving moisture availability that encourages root growth. Worms like a loose, moist soil as well, Mottern says. Their natural processes amend the soil as they assist in breaking down organic matter.

Mottern likes composted manures like Black Cow, and other organic sources of fertilizer. Composted products have much of their nutrient base already available for plants. You never want to add fresh kitchen waste or lawn clippings to your soil. Add these to your compost pile and make sure they are already broken down at least half-way before amending your soil with them.

Organic amendments are preferable to synthetic, Mottern says. They generally carry a low nutrient load and break down slowly in the soil, keeping plants and soil microbes in a state of harmony. Synthetic fertilizer can overload the soil with nutrients, thus encouraging rapid, unhealthy plant growth. If overused, these nutrients pollute stormwater runoff and contribute to algae blooms in our streams and wetlands.

Be mindful of temperature changes and your plants’ exposure. Freezing temperatures affect many plants, and low-lying areas tend to act as cold air sinks during the winter. A lower space can be 2 to 3 degrees cooler than surrounding higher ground. That makes a difference to many plants when the thermometer approaches freezing. Boulders, paving and building walls all help retain heat. Help protect cold-sensitive plants by planting them near these features. Orienting them facing south also helps, for maximum sun during the winter months.

If you’d like to learn more about planting, and about dozens of plant species that will fare well and look fantastic in your gardens, consider signing up for “Landscape Plants for North Carolina Gardens.” The class is limited to 15 students, so there is plenty of time for addressing gardeners’ questions and concerns. The fee is $105; $85 for Gardens members. Mottern’s summer plant class in this series (focusing on different plants) will run on Thursdays from May 31 to June 28, also from 10 a.m. to noon.

To register for this or other classes, or for more information, please call our registrar at 919-668-1707, or send an email. For more information about other classes and public events at Duke Gardens, please go to gardens.duke.edu.

Sarah P. Duke Gardens creates and nurtures an environment in the heart of Duke University for learning, inspiration and enjoyment through excellence in horticulture. The Gardens is at 420 Anderson St.

Columnist Kate Blakely is a graduate student at Duke Divinity School and a work-study assistant at Duke Gardens. This column first appeared in the Durham Herald-Sun.

Plant Sale & Fall Planting Tips

Our Fall Plant Sale will enhance
your garden year-round

By Kate Blakely

For all kinds of gardens, from vegetable to trees and shrubs, fall is best for planting. And the key in successful planting is in the roots. As plants go dormant in colder weather, they focus on their roots systems. Even planting in winter can work well, so long as the ground isn’t frozen and the plants receive proper care. Then, come spring, fall plantings will be already in the ground, ready to go.

We’ll have a wide range of plants available at our Fall Plant Sale Saturday from 9 a.m. to noon at Duke Gardens. Our horticulturists will also be on hand with expert advice. To start you on your way, horticulturist Michelle Rawlins offers a few fall planting tips below.

Soil Preparation: “Soil prep is your first task that you want to focus on when you’re starting a new bed,” says Rawlins. First, dig a hole a bit larger than the pot the plant came in. Make sure to break up any clay or compacted soil to allow proper drainage for your new plant. Add two to three shovel scoops of composted material to the soil you have removed from the hole. Blend all of this soil well. Remember, the key is in the roots, and having good soil is important.

“Compost does improve the quality of your soil and will produce a healthier specimen in your garden,” says Rawlins.

Planting: If the plant has been sitting in the pot for a while, it’s probably “root-bound.” Plants are usually initially grown in a soilless material along with PermaTill or vermiculite. These types of media make it really easy for the roots to grow. Inside a pot, fast-growing roots circle each other, forming a “root-ball.”

“If you don’t break the roots up, they’ll just continue to circle as if they’re still in the pot instead of in the ground,” Rawlins said. You need to break apart the root-ball gently before you plant.

“The hole should be no deeper than the root-ball,” Rawlins says. “If anything, you want to plant it about an inch or so higher than ground level, because the newly worked soil will settle, and if the plant’s too low, it has little success of thriving or even surviving.”

Cover any exposed root-ball with mulch. Rawlins recommends triple-shredded hardwood.

Watering and Fertilizing: Water the plant in well. Keep an eye on the plants for signs of thirst, like flagging or drooping. “They’ll let you know,” Rawlins says.

Be careful not to over-fertilize. “You don’t want to promote too much root growth in the fall,” Rawlins says. “You don’t want to push your plants too hard because of the threat of freezing.”

“Fall is a nice time to plant because you don’t have to water them every day,” Rawlins concluded. “The cool nights will be optimum for keeping your plant from too much stress or transplant shock.”

We’re happy to offer more advice at our Fall Plant Sale Saturday. And if you want first dibs, consider joining Friends of Duke Gardens to attend the 8 a.m. pre-sale (Friends info: 668-1711); you can join on site. Parking is free. The sale will feature bulbs best planted in (you guessed it!) the fall, as well as flowers, trees, vines and shrubs found throughout Duke Gardens all year. Read a more detailed preview in our previous post.

Sarah P. Duke Gardens creates and nurtures an environment in the heart of Duke University for learning, inspiration and enjoyment through excellence in horticulture. The Gardens is at 420 Anderson St. Visit online at gardens.duke.edu, or call 684-3698. For more information on Duke Gardens events, please see our education & events page, or read our quick blog roundup.

Kate Blakely is a graduate student at Duke Divinity School and a work-study assistant at Duke Gardens.